High surface area activated carbon has been made from carbon precursors such as synthetic resins e.g. phenolics and polyfurfuryl alcohol. Monolithic activated carbon structures can be made by first forming a structure from a precursor resin and then carbonizing and activating the structure. These structures are structurally superior to structures made from particulate activated carbon. For example, structures made by the above-described method are continuous activated carbon structures as opposed to discontinuous activated carbon derived from particulate activated carbon. This property affords better uniformity and strength of the activated carbon structure.
Typically a resin, after being shaped into a form, is cured first at relatively low temperature (&lt;200.degree. C.) where crosslinking takes place. The cured resin structure is then heat treated in an inert atmosphere to 600-1100.degree. C. to carbonize the resin. During carbonization, cross links are destroyed and low molecular weight organic compounds are removed with a resulting weight loss of about 50% for these high carbon yield resins. The remaining carbon is a mixture of amorphous and crystalline carbon. To create porosity in the carbon for adsorption, the amorphous carbon is preferentially removed by oxidation with carbon dioxide or steam. The pores with pore diameters smaller than 3-4 nanometers cause adsorption of various species on the carbon surface. These carbons are excellent adsorbers.
At present, activated carbon structures such as honeycombs are fabricated for various applications. One disadvantage of these structures is that because of the activation conditions, i.e., oxidation at high temperatures, the carbon surface has a high oxygen concentration. High oxygen concentration is not desirable in applications such as water purification, batteries, etc. However, if the carbon is not activated, the resulting low porosity carbon with low surface area cannot be optimally used in these applications.
Therefore a need exists to produce continuous high surface area carbon with low oxygen concentration.
The present invention provides such as method.